Instant liquid heater



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LMENTS Oct. 28, 1952 Filed June 22, 195o Oct. 28, 1952 H. c. A. MEYER 2,616,023

INSTANT LIQUID HEATER Filed June 22, 1950 6 Sheets-Sheet 2 OUT INVENTOR. Hav/Py 6 f4 /Vfyf/P HTTPIVFS Oct. 28, 1952 H, Q A, MEYER 2,616,023

INSTANT LIQUID HEATER Filed June 22, 1950 6 SheetsQ-Sheet 3 INI/ENTOR. #fn/Py C /Q /Vfyf/P Oct. 28, 1952 H. C. A. MEYER INSTANT LIQUID HEATER 6 Sheets-Shea?l 4 Filed June 22, 1950 INVENTOR. HCF/VP# 6. ,Q /Vfyf/P Oct. 28, 1952 H. c. A. MEYER INSTANT LIQUID HEATER 6 Sheets-Sheet 5 Filed June 22, 1950 l E IN INVENTOR.

#ffy/Pr C. ,Q M55/5P BY 054W ATTO/warns' Oct. 28, 1952 H- Q A MEYER 2,616,023

INSTANT LIQUID HEATER Filed June 22, 1950 6 Sheets-Sheet 6 OUT i E. INVENToR.

,N Hav/PV C.' ,4. Ufff/P Patented Oct. 28, 1952 UNITED STATES yPATENT GFFICE NSTNT LIQUID HEATER Henry C. A. Meyei'-,1Syracuse, N. Application June 22, y1950, SerialNo. ,169,707

12 Claims. 1

rihis invention relates to instant liquid heaters for generating vapor, and more particularly to Water heaters of the quick response type for generating steam.

One object of my invention is to provide a quick response steam generator provided with heating elements having a high B. t. u. input per unit of volume.

Another object of my invention is to provide such a steam generator employing a minimum amount of liquid per B. t. u. of input capacity.

Another object of ymy invention is to provide such a steam generator in which the heating elements are out of contact with the liquid and yet one in which structural elements directly opposing and exposed to the heating elements can be protected, by Contact of a surface of the element with a layer of the liquid, against heatinduced fatigue of the material of which the element is composed.

A further object of my invention is to provide such a steam generator having easily removable and replaceable liquid pans or trays for the retention of the liquid during the heating thereof,

having such relative placement of the heating elements and the pans that salts or other deposits from the liquid do not retard the heattr sier rate.

Still a further object of my invention is to provide such a steam generator in which the steam may be superheated.

These and other objects of my invention will be more apparent from the following description when taken with the accompanying drawings, in which:

Fig.

i shows a side elevation view of a steam generator in accordance with my invention;

Fig. 2 is a vertical cross section of the View through the body of the steam generator;

Fig. 3 is a cross-sectional view along plane lli-III of Fig. 2;

Fig. fi is a partial vertical cross-sectional view along plane IV-IV of Fig. 3;

Fig. 5 is a vertical cross-sectional view showing the terminal construction for the electrical connections;

Fig. 5 is a wiring diagram of the control circuit for the steam generator;

Fig. 7 is a partially cut-away plan View of an alternative embodiment for developing superheated steam;

Fig. 8 is a vertical cross-sectional view taken alongT plane VIII-VIII of the alternative embodiment of 7; and

Fig. 9 is a vertical cross-sectional View taken 2 along plane IX-'IX of the alternative embodia ment'of Fig."7.

Referring now to Figs. 1 and 2, the body ofthe steam generator comprises upper and llower dished heads III and II securing a cylindrical shell I2 therebetween as by means of Abolts vand nut connections I3. Asshown'in Fig. 2, metallic ring gaskets I5 and I6 are provided between cylindrical shell I2 and heads I and II, respectively, to seal the unit thus formed against the steam pressure which is developed therewithin. Outlet pipes I8 and I9 `are provided from the'upper and lower heads respectivelyand valve 25 is connected to control lthe discharge from outlet pipe `I 8 and valve 2 I 'is simi-larlyconnected to control tne discharge from outlet pipe I9. Between outlet pipe I9 and valve 'Z'I are preferably connected'a Asteam gauge 22, a pressure-sensitive'device or switch 23, hereinafter termed a pressure'- stat, and a safety valve 24. An inlet pipe 25 is provided in upper head I0 andan electricallyoperated control valve -26 is connected in the inlet pipe 0r line 25 to control the flow of the liquid into the steam generator in a manner described hereinafter in detail in connection with its operation.

The details of theY internal construction of the steam generator are shown in Fig. Y2, to which reference is now made. Mounted Within the cylindrical shell I2 are a plurality of pans orv trays 38-34 arranged vertically one above the other, as shown, in a stack. Inlet pipe 25 extends do-wn so 'as nearly to touch the bottom o'f upper pan 30. At the periphery of each pan o'r tray 30-34 are provided a number of -spacer bars 35 (see also Fig. 3) to center the generally circular pans Within the cylindrical shell I2. On the bottom of each pan 30-34 are disposed four metallic separator clips 31, as best seen in Fig. 3, and mounted upon these cli-ps -31 are two parallel ceramic insulating heating element holders 38 and 39 (see also Fig. 3V). The lowermost or inferior pan 34 rests upon and is supported by the responsive elements of three.temperature-sensi tive devices dil-42, hereinafter called thermostatic vswitches or thermostats These three thermostatic switches 40-42 are preferably arranged at the apices of a triangle and .indicated in dotted outline in Fig. 3. A plurality of'holddoWn `screws 44 are provided extending through the upper head I0 and bearing against the ceramic holders 38 and 39 of the uppermost or -superior pan 30 in order to hold the pans 30-34 firmly in the :position shown whenv these holddown screws 4'4 'are tightened. Two overflow pi-pes d5 are provided in the bottom of each pan Sil-33, these preferably being placed diametrically o-pposite one another and adjacent opposite edges of each pan. The upper edge or lip of each overilow pipe l5 is preferably raised only slightly above the bottom of its tray so that only a thin layer or film of the lliquid will cover the tray or pan bottom.

As shown in Figs. 3 and 4, each pan or tray Sli-3ft is not perfectly circular but has a portion of its periphery provided with a chord-like straight wall portion 5B, and to provide clearance for the electrical connections between the heating elements successive pans, from the top to the bottom of the stack, are so positioned that the straight wall portion 5D of one pair is disposed 180 from, or diagonally opposite to, the straight wall portion 5c of the next succeeding p-air.

Referring again to Fig. 2, channels 5l and 52 are cut in the inner sides of each of insulating holders 38 and 39, respectively, to receive electric heating elements 55-59, respectively, which as shown are of the grid type (see plan View of element 55 in Fig. 3). These heating elements are all connected in series, in the manner illustrated in respect of some of the elements by Figs. 3 and 4. Thus, as shown in plan view in Fig. 3, a U-shaped connection 6@ is connected to one end of a heating element and then passes above wall 5@ of pan 3e, thereafter extends downwardly and inwardly as shown in Fig. 4 to connect with the adjacent end of the next inferior grid heating element. The other end of the latter grid heating element is then connected in a similar manner by a connection (it to the adjacent end of the next inferior heating element. Suitable insulators 6i and S2 are provided on these connections 6B between adjacent heating elements, as illustrated in Figs. 3 and 4, to prevent each connection e@ from touching the adjacent pans.

The uppermost grid is provided at its other or free end with a connection 63 which is in turn connected to a terminal (not shown) extending through the upper head l@ in a manner similar to that in which the connection from the lowermost grid 59 is brought out through bottom head ll and as shown in Figs. 4 and 5. As there illustrated, the Vfree end of lowermost heating element 55 has electrical connection (i5 attached thereto and leading through insulators lil and @6 f for connection to terminal l! of Fig. 5 as indicated by the dotted lines. Terminal 'lll extends through lower head ll and includes a ceramic insulator bushing ll, a ceramic washer l2 and metallic washers i3 and le, preferably of copper disposed on opposite sides of head li and between bushing 'il and washers 'I3 and ffi, respectively. The central conductor of terminal 'lil is threaded and providedvwith inner and outer washers l5 and l respectively, washer 'l5 also being preferably of copper. When the assembly is tightened in place by means of nuts ll and 18 the copper washers 13, 14 and 'l5 seal the assembly to the lower head ll to seal the steam generator against the pressure therewithin.

Notethat as shown best in Figs. 3 and 4 the grid-type electric heating elements 55--59 lie generally in a plane between and parallel to pans or trays l0- 34%. While the heating elements may be of the flat grid type, prefer to form them of a cross section as shown best in Fig. 4 by bending each transverse portion extending between the insulating holders upward in a V-shape. This results in additional clearance between adjacent f. wire.

heating elements at their portions where they are unsupported, thus reducing the hazard of electrical snorting between these adjacent portions. Note that as indicated by the heavy arrows in Fig. 2 adjacent heating element 56 the heat from the element travels both upwardly and downwardly therefrom to heat the bottom of the pan above and the water of the pan below. The shape and configuration of the grid which I use thus provides a maximum heating surface and its placement in the manner described insures protection of the metal surfaces being heated because they are in contact with a layer of liquid. The only exception to this is the top dished head l0 which is directly exposed as shown in Fig. 2 to the upward radiation of heat from the uppermost heating element 55. However, head l0 may be somewhat cooled by being exposed to the surrounding air if enclosing insulation is not used, and in addition is made of heavier gauge material than the individual pans inasmuch as it must withstand the pressure within the steam generator. Alternatively, if desired and its heating effect is not needed, uppermost heating element may be omitted, thereby providing protection by contact with a layer of liquid for all surfaces directly opposing and exposed to the heating elements.

It will be observed from Figs. 2 and 3 that the overflow pipes le are disposed away from the heating elements -li and further in alternate trays or pans the heating elements are protected from possible splashing of the water dropping from the end of the overflow pipe l5 because of the interposition of the insulating heating element holders.

V/hile not shown because not susceptible of illustration, I preferably polish the inside surface of upper and lower heads l0 and Il, respectively, and cylindrical shell l2, as Well as blackening the top and bottom of each of pans or trays 3-34. This increases the rate of heat transfer to each pan (and thus to the water contained therein) while reducing the heat losses through the walls of the steam generator.

The operation of my steam generator is best explained by reference to Fig. 6, which is a circuit diagram of the electrical circuit controlling its automatic operation. As there shown, the circuit is supplied from a conventional three- Wire, 110-220 volt system with the heating elements 55-59 supplied from the 220-volt line Li-La and the control elements supplied from line L1-L2, L1 being the common or neutral The application of power to heating elements 55--59 is controlled by means of contacts 8l! under control of relay coil 5|, relay contacts being normally open, as indicated by the letters N. O. Relay coil 8l is connected in series with contacts 23a of pressure-stat 23 (Fig. 1) and contacts 4ta of high temperature thermostat 40 (Figs. 1 and 2). Contacts 23a and 40a are normally closed, as indicated by the letters N C. A second series circuit between lines Li j. and L2 is provided including the relay coil 25a of water valve relay 26 (Fig. l), contacts Ma of low water thermostat lll (Figs. 1 and 2), and the same contacts 23a of pressure-stat 23. Contacts Ma are normally open. It will be noted that only thermostats 4U and 4l of Fig. 2 have been referred to and shown as controlling contacts 40a and 4m of Fig. 6, respectively. The third thermostat 42, shown in Fig. 3, is preferably reserved as a spare and its controlling function therefore vnot utilized although, as pointed out above. it

aereo-see does serve as. a support for the lowermost or inferiorV pan 34.

In the normal operation of my steam generator', switches (not shown) are initially closed to apply power to lines L1, L2, and La of Fig. 6. Each of pans 35i- 34 are already lled with a film of water from previous operation, and since contacts 4m controlling water valve relay 26a are normally open, no further water initially flows into these pans. Contacts 23a, and 40a, being normally closed, however, cause current to ow through relay coil 8l and thus close contacts 80, thereby applying power' to heating elements F-59. Contacts 83 will remain closed until a too-high pressure is built up within the steam generator, causing pressure-stat contacts 23a to open, or until the temperature of the lowermost pan 34 becomes'too high, resulting in contacts 46a opening. Pressure-stat 23 is, of course, adjusted to operate at a desired maximum pressure and high temperature thermostat 48 is similarly set at the desired maximum ternperature of the lowermost pan 34. Low water thermostat 4l is set to operate at a predetermined temperature of lowerrnost pan 35i, this temperature, of course, being lower than the maximum temperature at which high temperature thermostat 4l) is set to operate. When lowermost pan 34 reaches this predetermined temperature, contacts 41a close and, since contacts 23a are normally closed, water valve relay 26a. is then energized, resulting in water being supplied to the pans 38-34 through electricallyoperated water control valve 25 (Fig. l). As shown best in Fig. 2, the water flows from the end of inlet pipe 25 into the uppermost pan 30, forms a thin layer or lm of water in this pan as controlled by the height of the upper lip of overflow pipe 45, and then ows through overflow pipes 45 into the next lower pan 3i. Each of pans 3-3`3 feed the next inferior pan until finally each of pans @Q -33 is covered with a thin layer or nlm of water oi the desired depth. Pan 33, due to being provided with overflow pipes 45, of course causes water to flow into lowermost or inferior pan 34, resulting in a dropping of the temperature of this pan. When the temperature of pan 34 drops below that predetermined value at which low water thermostat 4I is set to operate, contacts dia open and the ilow of water into the steam generator is shut oil. Preferably, this predetermined temperature at which low water thermostat 4I is set to operate is xed such that the level of water required to reduce the temperature of pan 34 to this predetermined temperature during normal operation of the steam generator is slightly less than the level of water maintained in each of pans 30-33 by the overflow pipes 45. The operation of the steam generator then continues automatically, additional water being supplied as necessary when the water in the pans is boiled away and the temperature of pan 34 therefore increased. In normal operation, with steam being withdrawn from my generator as it is produced, contacts 23a and 4M remain closed with contacts 4m opening and closing as necessary to provide the required amount of water to generate the steam withdrawn.

Note that pressure-stat contacts 23a are common to both the heating element and water supply control circuits and thus, rin the event that the pressure within the container or er1--v closure reaches the desired maximum pressure,

both further application ofpower'to the heating elements` and further admission of'water t'o'thepans is prevented.- Thus, whenmysteamlgen erator is-turned on but-steam-islnot being-with-l drawn therefrom, these pressure-stat contacts 3a* are effectively the controlling elementsV of the control circuit. This is-becausefas rapidlyl as the water in the pansisconverted-to steam, lowermost'pan 34 heats up and causes additionalVA water'to be admitted^ to the generator,` andintheV absence of aV pressure-controllingr element such as I have provided, thisprocess would-conf-4 tnuefif steam were not being withdrawn untill such a pressure weredeveloped that'the generatorwould explode'. Y

V'Ihea'bove description ofthe operation offmyl` steam'V generator` hasv assumed that the pans- 35--34 'are initially iilled with almbfwater, asA they usually are duettov previous `use of "theigen-" erator. The only difference inV operation" incase' that these-pansare not so'filled-isthat lowermostfV parr 34 will more-quickly reachthe'predetermined -4 temperature at which contactsV 41al close, where-- upon water valve relay 23a will bev` energized to supply water to the pans until each is fllledwith a film of water as described above, the 'opera--AY tion'otherwise4 being'the same as justdescribed. 'An alternative` embodimentofaA steam generator in accordancewith my invention'y andfpro-fvidingK a tortuous path forthe-stearn-"overthe'- heating elements in orderto 'produce-superman ing isshownin Figs; 7, Siand 9.

Fig. 7' is a partiallycut-awayplan viewfwith the` detail ofthep'anor tray `and heating Y'element' placement relative to one-another shown `irr-the i-lrstand` second quadrants, a view of the bottom interior-from` beneath the lowermost pan being" shown in' the third quadrant, and a' View from above of the completeassembly being v'shown in the fourth quadrant. Vertical cross-'sectional4 views'taken' along planes'VIII--V-III and IX-IX are'illustrated in Figs. Sand' 9.l The `construction ofthis alternative embodiment can best be-*understood by reference tov all three figures.

As there shown, this alternative embodiment` of a steam generator in accordanceA with my-invention comprisesupper and lower cup-shaped" containermembers and 85 held together` byV means of bolt and nut connections 81 at theffour corners thereof and sealed attheirjoint by means i of a metallicfring gasket 88.' Note that lower-container member 83 isprovided withl an integral encircling'collar'at its endV abuttingmember 85` and surroundingv thisI abutting'end of thel latter tostrengthen the joint andretain' the metallic sealing ring 83 between members 85-and 85. An outlet pipe 89- is threaded'in-'the center of the upper endV of top container member 85 and has.

upper ends and extend through apertures' pro-- vided in the lower end of container memberr,

being threaded thereat` and sealed tol andposi-f' tioned in member 83 by 'meansof' the nut and sealing washer arrangement 9| illustrated. Each tube 9B is provided with a shoulderv 92 adjacent the bottom of member 85 and interiorly thereof.:

Three ferrules 93 are stacked one atop anotheron each tube 90 with the bottom of the lowermost ferrule 93 abutting shoulder'92. Each ferrule-93 is also provided with an integral generally-V tri-- asia-02sv 7 singularly-shaped shelf-like planar portion 94 disposed at the upper end thereof upon which a ceramic insulating heating element holder 95 is supported, as illustrated in Figs. 7 and 8.

A pan or tray 96 is supported by and atop each pair of holders 95 disposed in the same horizontal plane. Each pan 96 is provided with arc-like inclined ends and straight vertically-disposed sides, the sides being positioned parallel to holders 95. as may be seen best in Figs. 7 and 8. The three pans 96 are staggered with alternate opposite ends touching the adjacent inner surface of container member 85, as shown best in Fig. 9, in order to provide a tortuous path from beneath the lowermost pan A95 around the left end thereof (Fig. 9), thence to the right between lowermost and middle pans 96 and around the right end of middle pan 96, thereafter to the left between uppermost and middle pans 96, and finally around the left end of uppermost pan 96 to the upper interior portion of container member 85, from whence the contained vapor is discharged through outlet pipe 89.

lAn overflow pipe 91 is provided in the bottom of each pan 95 with the pans preferably disposed such that the overflow pipes 91 of adjacent pans are positioned diagonally opposite one another and at respective opposite ends of adjacent pans, as shown in Fig. 9. Note that as was the case in the embodiment of Figs. 1-5, the upper edge or lip of each overflow pipe 91 is preferably raised only slightly above the bottom of its pan so that only a thin layer or film of the liquid being evaporated will cover the pan bottom. The pan assembly thus far described is firmly positioned together and secured in place by means of respective hold-down clamps 98 encircling each tube 90 and secured adjacent the top of the straight portion thereof by means of a nut 99. Each holddown clamp 98 abuts a second shoulder portion of its tube 99 and overlies and is bent slightly around the upper edge of the adjacent side of the uppermost pan 96, as best illustrated in Figs. 8 and 9.

A fourth pan or tray |05 is positioned beneath the lowermost pan 96 and atop the responsive elements of two temperature-sensitive devices |06 and |01, hereinafter called thermostatic switches or thermostats. Pan |05 is shaped similarly to pans 96 except that it is longer between its ends so that both its ends abut opposite sides of the interior surface of container member 86, as shown in Fig. 9, in order to denne the lower boundary of the tortuous path above described. It is to be noted that, as best shown in Fig. 7, each heating element holder 95 and each planar portion 94 of ferrules 93 extend in a chord-like fashion adjacent the sides of each pan 96 and provide the sealing side boundaries for the tortuous path above described.

A channel ||0 is cut in the inner side of each insulating holder 95 to receive an end of the respective electric heating element lll, which is of the same grid type described above (see plan view of element in Fig. 7). Three of these heating elements are provided, one between the uppermost and middle pans 96, one between the lowermost and middle pans 96, and one between the lowermost pan 96 and pan |05 immediately thereunder. Heating elements are all connected in series, U-shaped connection ||2 being provided from one end of uppermost heating element to the adjacent end of the middle heating element as shown in Fig. 7, and the diagonally-opposite end of middle heating element being connected to the adjacent end of lower heating element by means of U-shaped connector IIB, which may be seen in Figs. 8 and 9. Note that a tubular insulating member H4 is provided around the central portion of each electrical connector, although these are visible only in Fig. 7.

Terminals H5 and ||6 are provided sealed in the bottom of container member 86, their construction being similar to that of terminal l0 described above in connection With Fig. 5. U- shaped connector ||1 connects terminal ||6 to the free end of uppermost heating element (see Figs. 7 and 8) and a shorter U-shaped connector ||8 connects terminal ||5 to the free end of lowermost heating element (see Fig. 9).

The operation of the steam generator of Figs. 7-9 is similar to that of the embodiment of Figs. 1 5 described above in connection with Fig. 6, and hence will not be repeated here in detail except to point out that 4the water inlet connections are made to the lower ends of each of tubes and the water flow is controlled by a suitable electrically-operated water valve (not shown) similar to water valve 26 of Fig. 1. Also, a suitable pressure-stat (not shown) similar to pressure-stat 23 of Fig. 1 is connected to outlet pipe 89. The control circuit is the same as that shown in Fig. 6 with one of thermostats |06, |07 being adjusted to operate as the high temperature thermostat and the other adjusted so as to operate as the low water thermostat, the respective switch contacts of each being normally closed or normally open as required and indicated in Fig. 6 for its particular function. Note that, as described above, the feed water initially fows into the uppermost pan 96, forming a film on the bottom thereof, and overflows from each superior pan into the next inferior pan, the level of the water in the lowermost pan being controlled by the combined action of the two thermostats |06, |91. Note again that due to the tortuous path provided, as explained above, vapor or steam produced in the lowermost pan |05 is superheated as it successively passes adjacent the two upper heating elements Similarly, the steam produced in lowermost pan 95 is superheated as it passes adjacent the uppermost heating element ||I.

Thus I have provided in the embodiment shown in Figs. rI--9 a steam generator which is very easily and quickly assembled and disassembled. In the initial assembly, thermostats |96 and |01 are rst inserted in their respective apertures provided in container member 86. Pan |05 is then placed within container member 06 atop the responsive elements of thermostats |09, |97. Next the three ferrules 93 are slid over each tube 90, and each tube assembly thus formed then secured in the apertures provided in the bottom of the container member 90 by means of its nut and sealing washer connection 9|. An insulating holder'95 is next positioned atop each of opposed planar shelf portions 94 of ferrules 93, and a pan 96 placed atop each pair of holders 95 disposed in the same horizontal plane. Hold-down clamp 98 and nut 99 are then slipped in turn over the upper end of each tube 90 and the assembly thus far described secured in place by tightening each nut 99. The three heating elements |I| are next inserted in the opposed channels ||0 provided in each pair of insulating holders 95 lying in the same horizontal plane and the electrical series connections thereafter made between the respective heating elements III and terminals H and H6. Lastly, cup-shaped container member 85 is placed over the assembly as shown with gasket 88 positioned between members 35 and 8B and the-unit thus formed secured together by means of bolt and nut connections 81.

Note particularly that in the embodiment of Figs. 7-9, since no heating elements are positioned above uppermost pan 9B or below lowermost pan |05, protection is provided by contact with a layer of liquid for all surfaces directly opposing and exposed to the heating elements l.|.-I.

While I have described particular embodiments of my invention as required, the principles of myinvention are of broader application in ways which will be apparent to those skilled in the art. Numerous additional applications of these principles will occur to those skilled in the art vand no attempt has here been made to exhaust such possibilities. The scope of my invention is defined in the following claims.

What I claim is:

1. A. liquid heater including in combination: a container; a plurality of pans disposed at different levels within said container; means for maintaining a layer of liquid in said pans; and a radiant heating element positioned within said container at a level between the bottom of an upper one of said pans and the exposed surface of the liquid in the next lower of said pans, said bottom and said surface being exposed to said element for radiation heating thereby.

2. A liquid heater including in combination: a container; a plurality of pans disposed at different levels within said container; means for supplying liquid to said pans; means for limiting the depth of liquid accumulating in each of said pans; and a radiant heating element positioned within said container at a level bctween the bottom of an upper one of said pans and the exposed surface of the liquid in the next lower of said pans, said bottom and said surface being exposed to said element for radiation heating thereby.

3. A liquid heater including in combination: a container; a plurality of pans disposed at diiferent levels within said container; means for supplying liquid to said pans; means 'for limiting the depth of liquid accumulating in each ci said pans and including control means for said iirst-mentionedmeans and responsive to the presence. ofV liquid in. the lowermost of said pans for maintaining a layer of liquid in each of said pans; and a radiant heating element positioned within said container at a level between the bottom of an upper one of said pans and the expo-sed surface or" the liquid in the next lower of said pans, said bottom and said surface being exposed to said element for radiation heating thereby.

4. A liquid heater including in combination; a container; a plurality of pans disposed at diierent levels and parallel to one another within said container; means for supplying liquid to said pans; and a radiant hea-ting element positioned within said container at a level between the bottom of an upper one of said pans and the exposed surface of the liquid in the next lower of said pans, said heating element lying generally in a plane parallel to said bottom of an upper one of said pans and said exposed surface of the liquid in the next lower of said pans and having its opposed surfaces directly exposed thereto.

5. A lsteam generator comprising in combination: a container having water inlet and steam outlet openings; a plurality of pans disposed at diierent levels within said container with the uppermost of said pans being fed from said water inlet; overflow means for each superior pan feeding the next inferior pan; a radiant electric heating element positioned between each pair of adjacent pans to heat the bottom oi the superior pan and the water surface of the inferior pan; a thermostatic switch including a responsive element disposed within said container abutting the lowermost pan and electric contacts controlled thereby; and an electric circuit including in series said heating element and the electric contacts of said thermostatic switch to control the application of power to said heating element inaccordance with the temperature of said lowermost pan.

6. A steam generator comprising in. combination: a container having vwater inlet and steam outlet openings; a valve connecting said water inlet to a water source, and including electricallyoperated actuating means therefor; a plurality of pans disposed at diierent levels within said container with the uppermost of said pans being fed from said water inlet; overflow means for each superior pan feeding the next inferior-pan; a radiant electric heating element positioned between each pair of adjacent pans to heat the bottom. of the superior pan and the water surface of the inferior pan; a thermostatic switch including a responsive element disposed within said container abutting the lowermost pan and electric contacts controlled thereby; and an electric circuit including in series said electricallyoperated actuating means of said valve and the electric contacts of said thermostatic switch to control the ow of water into the pans of said container in accordance with the temperature of said lowermost pan.

7. A liquid beater and vapor generator cornprising in combination: a container having liquid inlet and vapor outlet openings; a plurality of pans disposed at different levels within said container with the uppermost of said pans being fed from said liquid inlet; overflow means for a superior pan feeding the next inferior pan and positioned to maintain a layer of liquid of limited depth in the superior pan; and a radiant heating element positioned between said pair of pans to heat the bottom of the superior pan and the liquid lsurface of' the .inferior pan, said bottom and said surface being exposed to said element for radiation heating thereby.

8. A steam generator comprising in combination; a container having. water inlet and steam outletl openings; a valve connecting said water inlet to a water source, and including electrically-operated actuating means therefor; a plurality of pans disposed at different levels within said container with the uppermost pan fed from said water inlet; overflow means for a superior pan feeding the next inferior pan; a radiant electric heating element positioned between said pair of pans to heat the bottom of the superior pan and the water surface of the inferior pan; rst and second thermostatic switches, each including a responsive element disposed within said container abutting said inferior pan and electric contacts; and a first electric circuit including in series said heating element and the electric contacts of said first thermostatic switch and a second electric circuit including in series said electrically-operated actuating means of said valve and the electric contacts of said second thermostatic switch to control the application of power to said heating element and to control the oW of water into the pans of said container, respectively, in accordance with the temperature of said inferior pan.

9. A steam generator comprising in combination: a container having water inlet and steam outlet openings; a pressure-sensitive switch connected to said outlet opening and including electric contacts; a valve connecting said water inlet to a water source, and including electricallyoperated actuating means therefor; a plurality of pans disposed at different levels within said container with the uppermost pan fed from said water inlet; overflow means for a superior pan feeding the next inferior pan; a radiant electric heating element positioned between said pair of pans to heat the bottom of the superior pan and the water surface of the inferior pan; first and second thermostatic switches, each including a responsive element disposed within said container abutting said inferior pan and electric contacts controlled thereby; a first electric circuit including in series said heating element, the electric contacts of said pressure-sensitive switch,

' and the electric contacts of said first thermostatic switch to control the application of power to said heating element in accordance with the temperature of said inferior pan and the pressure developed within said container; and a second electric circuit including in series said electrically-operated actuating means of said valve and the electric contacts of said second thermostatic switch to control the flow of water into the pans of said container solely in accordance with the temperature of said inferior pan.

10. A liquid heater and vapor generator comprising in combination: a container having liquid inlet and vapor outlet openings; a plurality of pans disposed at different levels within said container with the uppermost of said pans being fed from said liquid inlet; overflow means for a superior pan feeding the next inferior pan and positioned to maintain a layer of liquid of limited depth in the superior pan; and a radiant electric heating element for and positioned above each pan to heat the liquid surface of the pan.

l1. A liquid heater and superheated Vapor generator comprising in combination: a container having liquid inlet and vapor outlet openings; a plurality of pans disposed at different levels within said container with the uppermost of said pans being fed from said liquid inlet, each superior pan being of less width than said container and said superior pans being staggered vertically within said container with respective opposite ends of adjacent superior pans abutting opposite sides of said container to form a tortuous path for the vapor from the bottom to the top of the container; sealing means disposed between adjacent sides of adjacent pans to conne 6 the vapor to said tortuous path; overflow means for each superior pan feeding the next inferior pan and positioned to maintain a layer of liquid of limited depth in the superior pan; and a radiant electric heating element positioned between each pair of adjacent pans to heat the bottom of the superior pan and the water surface of the inferior pan and the vapor therebetween.

12. A superheated steam generator comprising in combination: a container having water inlet and steam outlet openings; a pressure-sensitive switch connected to said outlet opening and including electric contacts; a valve connecting said water inlet to a water source, and including electrically-operated actuating means therefor; a pluralityl of pans disposed at different levels within said container with the uppermost pan fed from said water inlet, each superior pan being of less width than said container and said superior pans being staggered vertically within' said container with respective opposite ends of adjacent superior pans abutting opposite sides of said container to form a tortuous path for the steam from the bottom to the top of the container; sealing means disposed between adjacent sides of adjacent pans to confine the steam to said tortuous path; overow means for each superior pan feeding the next inferior pan; a radiant electric heating element positioned between each pair of adjacent pans to heat the bottom of the superior pan and the water surface of the inferior pan and the steam therebetween; first and second thermostatic switches, each including a responsive element disposed within said container abutting the lowermost pan and electric contacts controlled thereby; a rst electric circuit including in series said heating element, the electric contacts of said pressure-sensitive switch, and the electric contacts of said first thermostatic switch to control the application of power to said heating element in accordance with the temperature of said lowermost pan and the pressure developed within said container; and a second electric circuit including in series said electricallyoperated actuating means of said valve and the electric contacts of said second therrnostatic switch to control the flow of water into the pans of said container solely in accordance with the temperature of said lowermost pan.

HENRY C. A. MEYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,639,953 Miller Aug. 23, 1927 2,179,781 Frankel et al Nov.f14, 1939 2,235,303 Stucker Mar, 18, 1941 2,427,476 Schick Sept. 16, 1947 

